Motilin
The hormone behind the stomach's contractions between meals, measured and infused in people since the 1970s
Motilin is released from endocrine cells of the duodenum and upper jejunum. Its blood level rises and falls in a cycle during fasting, and each peak is followed by a wave of strong contractions that starts in the stomach and sweeps the small intestine. Infused into volunteers it triggers those contractions early and raises hunger; infused into people with diabetic gastroparesis it sped stomach emptying. It lasts minutes in the blood and has never been developed as a drug.
Used in human trials: 10 pmol/kg/min, Continuous infusion, Intravenous (Study: diabetic gastroparesis, 6 patients (double-blind crossover)) Details ↓
Recommended Dosing
Used in human trials
No manufacturer dose exists for this use: these are amounts given in published trials, not recommendations.
What is it?
Motilin is a short peptide hormone made by endocrine cells in the lining of the duodenum and jejunum. Measured with a specific assay in 1976, the human duodenum held about four times as much as the jejunum and the rest of the gut almost none; fasting blood levels in 100 healthy people ranged from under 5 to 300 pmol/l. The same cells also make ghrelin, its relative.
Its job shows during fasting. Between meals the gut runs a cycle called the migrating motor complex: a quiet phase, a phase of irregular contractions, then phase III, a band of strong contractions that clears the stomach and small intestine. In healthy volunteers a motilin peak came before each activity front that began in the stomach, and motilin rose about 35% just before a gastric phase III but barely before one that began in the duodenum. Bile entering the duodenum was followed by motilin release.
Giving motilin reproduces this. Pure motilin infused into fasting volunteers brought the next activity front forward from more than two hours to about 46 minutes, even at a rate that raised blood levels only slightly. Later work found that hunger scores peak during a motilin-driven gastric phase III, and that people who had lost their appetite without explanation lacked that phase.
Motilin has been tested in patients only as short research infusions. In two small studies of diabetic gastroparesis, an intravenous infusion sped the emptying of liquid, solid and semisolid meals. Given with a meal to healthy volunteers, it made the stomach return to its resting volume sooner after the meal and increased nausea. Levels differ in several conditions: lower after meals in irritable bowel syndrome, higher across the fasting cycle in obesity, and high in most patients with small cell lung cancer.
Motilin is not a medicine anywhere. Its half-life is under five minutes, and drug development has gone to separate molecules that act on its receptor, which are not covered here.
Mechanism of Action
Motilin is released from the upper small intestine in a cycle during fasting and acts on motilin receptors in the stomach wall, most of them on nerves, to start the strong contractions that clear the stomach between meals.
The fasting motor cycle
Plasma motilin peaks before the phase III contractions that begin in the stomach, and infusing it brings the next phase III forward.
Hunger signal
Hunger scores rise during a motilin-driven gastric phase III and track plasma motilin in fasting volunteers.
Cholinergic nerves
Its effect on the antrum needs muscarinic nerve signalling, which high-dose atropine blocks; receptors in human antrum sit mainly on nerves.
Published Research
These are studies of motilin itself, read from their PubMed abstracts: measurements of the hormone in healthy people and patients, short research infusions in volunteers and in diabetic gastroparesis, one study of human stomach tissue, and four reviews. Studies of drugs that act on the motilin receptor are not carded here.
Motilin peaks come before the fasting activity front
In 14 fasting volunteers, activity fronts came every 137 minutes on average and each was preceded by a motilin peak about 25 pmol/l above the low after the previous front. Infusing pure porcine motilin, the same sequence as human, set off an activity front in 12 of 16 volunteers and cut the interval to 46 minutes, even at 0.4 pmol/kg/min, a rate that raised plasma motilin by only 57 pmol/l.
Motilin, not ghrelin, rises before gastric phase III
Sampled across a full fasting motor cycle with high-resolution manometry, plasma motilin differed between the phases and rose by about 35% before a phase III that started in the stomach, against 3% before one that started in the duodenum. Total and active ghrelin did not change with the phases.
Motilin-driven stomach contractions signal hunger
In fasting volunteers, hunger scores were higher during a gastric phase III than during phases I and II, and they correlated with plasma motilin. Infused motilin, but not ghrelin, set off an early gastric phase III with a rise in hunger. Patients with unexplained loss of appetite had no gastric phase III and lower hunger ratings.
Faster gastric emptying in diabetic gastroparesis
In a double-blind crossover study of six patients with severe diabetic gastroparesis, motilin infused at 10 pmol/kg/min for 90 minutes around breakfast cut the half-emptying time of liquids from 51 to 22 minutes and of solids from 111 to 51 minutes. The authors estimated the effective infusion rate at about 4 pmol/kg/min from the rise in plasma motilin.
Gastroparesis emptying brought to normal
Nine insulin-dependent diabetic patients with gastroparesis emptied a labelled semisolid meal more slowly than 11 healthy controls; during an intravenous motilin infusion their emptying sped up until it no longer differed significantly from the controls'.
After a meal: faster stomach recovery, more nausea
In a randomised, placebo-controlled study, ten fasted volunteers drank a 200 ml liquid meal at the start of a 90-minute intravenous infusion of synthetic motilin or placebo. Gastric relaxation after the meal was the same, but with motilin the stomach returned to its baseline volume sooner, and feelings of nausea after the meal increased.
Its stomach effect runs through cholinergic nerves
In 27 healthy volunteers, a 10-minute infusion of synthetic human motilin (50 ng/kg) started an early antral phase III in every subject given saline beforehand. High-dose atropine blocked that response in all subjects, while a duodenal phase III still appeared, so the antral effect depends on muscarinic nerves and the duodenal one does not.
Cleared from blood in under five minutes
In six healthy volunteers, the body's own motilin, suppressed with somatostatin, disappeared with a half-time of 4.56 minutes. An infused synthetic analogue with norleucine at position 13 gave 4.36 minutes, a distribution volume of 49.4 ml/kg and a clearance of 7.8 ml/kg per minute; both forms were eliminated by first-order processes.
First assay: where motilin is and how much circulates
A specific radioimmunoassay found 165.7 pmol of motilin per gram of human duodenum, 37.5 in the jejunum and negligible amounts in the rest of the gut. Fasting plasma motilin in 100 healthy subjects ranged from under 5 to 300 pmol/l, with a mean of 72.
Bile flow releases motilin
Over 46 hours of recordings in 16 volunteers there were 29 episodes of gallbladder emptying, 27 motilin peaks and 23 activity fronts. Bile output into the duodenum was followed by a significant rise in plasma motilin, which then fell after each activity front.
Higher in obesity, lower after gastric bypass
Obese patients had higher plasma motilin than controls across the fasting cycle but tended to lack the peak before phase III, and their hunger during phase III was lower. After gastric bypass surgery, motilin fell, in parallel with hedonic hunger scores, while ghrelin did not.
Less motilin after meals in irritable bowel syndrome
In 18 patients with irritable bowel syndrome and 11 controls, the patients released less motilin after drinking water and after a fat-rich meal, while the fat meal gave them an exaggerated and prolonged cholecystokinin release.
Raised in small cell lung cancer
Plasma motilin was high in 17 of 20 patients with small cell lung cancer. Above 900 pg/ml it marked that cancer with 59% sensitivity and 78% specificity, but tumour tissue held little motilin, so the source of the excess was not found.
Human motilin sequenced from a tumour
An extract of a liver metastasis from a patient with high plasma motilin held 3.37 micrograms of motilin per ml. The purified peptide was sequenced and found identical to porcine motilin, the first report of a tumour containing large amounts of the hormone.
Made in the same cells as ghrelin
Mapping of biopsies from the whole human gut found ghrelin and motilin produced in the same endocrine cells of the duodenum and jejunum and stored in the same secretory granules, pointing to their release together; plasma profiles of the two ran in parallel in pigs.
Its receptors sit mainly on stomach nerves
Binding of radiolabelled motilin to membranes from human stomach and duodenum was highest in the antrum and mostly in the nerve fraction. Receptors from nerve and muscle preparations bound two motilin fragments with different affinities, suggesting receptor subtypes that differ from the rabbit's.
A hormone in the ghrelin family
Motilin, made by duodenal endocrine cells, belongs to the same peptide family as ghrelin, whose gene also encodes obestatin. The review notes agonists and antagonists of the motilin receptor emerging for clinical use in digestive dysmotility.
From motility to hunger
Rodents carry the motilin gene and its receptor only as pseudogenes, which slowed research, but studies in the five years before this review tied motilin to hunger and food intake in healthy people and in disease; bitter tastants in the gut change its release.
Motilin across vertebrates
Motilin from endocrine cells of the upper intestine mediates phase III of the fasting motor complex in the stomach of humans, dogs and house musk shrews through its receptor, and motilin-induced phase III sends a hunger signal from stomach to brain; its roles in other mammals are less clear.
Functions beyond the fasting cycle
Besides the migrating motor complex, motilin affects lower oesophageal sphincter pressure, gastric accommodation, gallbladder contraction and the secretion of pepsin, pancreatic juice and insulin. Gastric acid and bile are its main triggers, bitter substances lower it, and drugs targeting its receptor have not reached clinical use.
Dosing Data
Motilin is not approved anywhere as a medicine. These are research infusion rates from published human studies, as stated in their abstracts; none was a treatment course.
Educational information, not medical advice. Each dose above is tagged with its source: an approved label, a published human study, animal data, or amounts reported by users. None is a recommendation for you. An unapproved compound has no established safe or effective human dose, and products sold for “research use only” are not made or tested for people. Talk to a doctor before acting on anything on this site, including before you start, stop or change any medicine or dose. Full medical disclaimer.
What a Buyer Needs to Know
What is sold, how it is mixed, stored and taken, and what is known about its safety, quality and legal status. Each part names its source. Where we have none, it says unknown.
What is sold
Unknown: we hold no label and no published test that says what forms or vial sizes Motilin is sold in. A vial's own label is a seller's claim, not a source.
Mixing a vial: a worked example
No worked example: none of the doses on this page is a fixed amount in mg or mcg injected under the skin or into a muscle (the routes given are: intravenous). There is no home-mixing step to show. The reconstitution calculator does the arithmetic for any vial.
Source: the route and amount of each dose row in Dosing Data below.
Storage before and after mixing
Unknown: no label or published stability study on file says how to store Motilin, before or after mixing. The mixing guide sets out the general rules, with their sources: keep a mixed vial in the fridge, and use it promptly, as the bacteriostatic water label says of any drug dissolved in it. The 28 days often quoted is the limit for an opened multiple-dose vial from a manufacturer, an outer limit set for sterility, not a time a mixed solution has been shown to keep. Nobody has published how long Motilin stays intact once mixed.
How it is taken
As it was given in human studies: Intravenous (Continuous infusion; Study: diabetic gastroparesis, 6 patients (double-blind crossover)).
For injection technique, sites and needle disposal, see the mixing guide.
Source: Used in human trials: the route and frequency of each row in Dosing Data below.
What to expect, and when
How long it stays in the body: a half-life of about 4.6 minutes for the body's own motilin; 4.4 minutes for an infused synthetic analogue (PMID 832789). After about five half-lives almost none is left.
How long the doses were given: Study: diabetic gastroparesis, 6 patients (double-blind crossover): 90 minutes, starting 5 minutes before breakfast; Study: healthy volunteers, fasting motility (lowest rate that worked): Started early in the quiet phase of the fasting cycle; Study: healthy volunteers, antral motility: 10 minutes.
When effects appear: unknown; no source on this page gives a time to effect for Motilin. Results reported in the studies are under Published Research.
Source: half-life: PMID 832789; Used in human trials, the duration of each row in Dosing Data below.
Side effects, and when to stop or get help
From the Side Effects section: More nausea after a meal during a motilin infusion, with a trend towards more abdominal pain and tension (PMID 12184523); No safety data beyond single infusions lasting minutes to hours. Full list and cautions ↓
When to stop or get help: unknown; no label or trial on file sets rules for stopping Motilin. Treat a severe or unexpected reaction as a reason to stop and see a doctor.
Source: the Side Effects section below (“From the short infusion studies above, which reported little on safety”).
Interactions
Unknown: a PubMed search for human interaction studies of Motilin (reviewed 2026-10-28) found none. Unknown is not the same as safe to combine.
Every peptide's record, with its source: the interaction matrix.
Checking what you bought
Unknown: no published independent test of Motilin products is in our lab-results database yet, so how products sold under this name measure up is not known.
To read a certificate of analysis, paste it into the COA decoder; it checks the measured mass against Motilin's expected mass, 2,699.1 Da, from this entry's molecular data. Trust & Verification explains what independent testing can and cannot show.
Legal status
US: Research Chemical (Not a medicine anywhere in the sources read). Sport: Prohibited (S0 catch-all).
Country by country ↓ · Regulatory tracker
Source: this entry's approval status and the WADA Prohibited List, as in Legal Status below.
Side Effects & Contraindications
Reported Side Effects
From the short infusion studies above, which reported little on safety.
Contraindications & Cautions
No product label exists. These cautions follow from the evidence.
Legal Status
Motilin is a research peptide; it is not approved as a medicine anywhere in the sources read.
Frequently Asked Questions
?What does motilin do?
Between meals it starts the strong wave of contractions, phase III of the migrating motor complex, that begins in the stomach and clears it. Its plasma peaks come just before those waves.
?Does motilin make you hungry?
In fasting volunteers, hunger rose during motilin-driven stomach contractions and tracked plasma motilin, and infused motilin raised hunger along with an early phase III.
?Has motilin been tried as a treatment?
Only in short research infusions. In small studies of diabetic gastroparesis it sped stomach emptying during the infusion; it has never been developed as a medicine.
?How long does motilin last in the blood?
About four and a half minutes: the body's own motilin disappeared with a half-time of 4.56 minutes in six healthy volunteers.
?Is motilin related to ghrelin?
Yes. They belong to the same peptide family, and in the human duodenum and jejunum the same cells make and store both.
?Why is motilin not studied in mice?
Rodents carry the motilin gene and its receptor only as pseudogenes, so studies use humans, dogs and house musk shrews.
References
- [clinical-trial] Vantrappen G, et al. "Motilin and the interdigestive migrating motor complex in man." Dig Dis Sci, 1979;24(7):497-500. PMID: 456236.
- [pubmed] Deloose E, et al. "Endogenous motilin, but not ghrelin plasma levels fluctuate in accordance with gastric phase III activity of the migrating motor complex in man." Neurogastroenterol Motil, 2015;27(1):63-71. PMID: 25393165.
- [clinical-trial] Tack J, et al. "Motilin-induced gastric contractions signal hunger in man." Gut, 2016;65(2):214-24. PMID: 25539673.
- [clinical-trial] Peeters TL, et al. "Effect of motilin on gastric emptying in patients with diabetic gastroparesis." Gastroenterology, 1992;102(1):97-101. PMID: 1727784.
- [clinical-trial] Schmid R, et al. "Effect of motilin on gastric emptying in patients with diabetic gastroparesis." Diabetes Care, 1991;14(1):65-8. PMID: 1991439.
- [clinical-trial] Kamerling IM, et al. "Exogenous motilin affects postprandial proximal gastric motor function and visceral sensation." Dig Dis Sci, 2002;47(8):1732-6. PMID: 12184523.
- [clinical-trial] Boivin M, et al. "Neural mediation of the motilin motor effect on the human antrum." Am J Physiol, 1997;272(1 Pt 1):G71-6. PMID: 9038878.
- [pubmed] Mitznegg P, et al. "Pharmacokinetics of motilin in man." Gastroenterology, 1977;72(3):413-6. PMID: 832789.
- [pubmed] Bloom SR, et al. "Measurement of human plasma motilin." Scand J Gastroenterol Suppl, 1976;39:47-52. PMID: 1069363.
- [pubmed] Nilsson BI, et al. "Relationship between interdigestive gallbladder emptying, plasma motilin and migrating motor complex in man." Acta Physiol Scand, 1990;139(1):55-61. PMID: 2356758.
- [pubmed] Deloose E, et al. "Higher plasma motilin levels in obese patients decrease after Roux-en-Y gastric bypass surgery and regulate hunger." Gut, 2016;65(7):1110-8. PMID: 25986945.
- [pubmed] Sjölund K, et al. "Disturbed motilin and cholecystokinin release in the irritable bowel syndrome." Scand J Gastroenterol, 1996;31(11):1110-4. PMID: 8938905.
- [pubmed] Noseda A, et al. "Increased plasma motilin concentrations in small cell carcinoma of the lung." Thorax, 1987;42(10):784-9. PMID: 2892280.
- [pubmed] De Clercq P, et al. "Purification and amino acid sequence of human motilin isolated from a motilin containing liver metastasis." Regul Pept, 1995;55(1):79-84. PMID: 7724830.
- [pubmed] Wierup N, et al. "Ghrelin and motilin are cosecreted from a prominent endocrine cell population in the small intestine." J Clin Endocrinol Metab, 2007;92(9):3573-81. PMID: 17595255.
- [pubmed] Miller P, et al. "Motilin receptors in the human antrum." Am J Physiol Gastrointest Liver Physiol, 2000;278(1):G18-23. PMID: 10644557.
- [review] Poitras P, et al. "Motilin." Curr Opin Endocrinol Diabetes Obes, 2008;15(1):54-7. PMID: 18185063.
- [review] Deloose E, et al. "Motilin: from gastric motility stimulation to hunger signalling." Nat Rev Endocrinol, 2019;15(4):238-250. PMID: 30675023.
- [review] Kitazawa T, et al. "Motilin Comparative Study: Structure, Distribution, Receptors, and Gastrointestinal Motility." Front Endocrinol (Lausanne), 2021;12:700884. PMID: 34497583.
- [review] Mori H, et al. "Physiological functions and potential clinical applications of motilin." Peptides, 2023;160:170905. PMID: 36436612.
- [pubmed] Luiking YC, et al. "Effects of motilin on human interdigestive gastrointestinal and gallbladder motility, and involvement of 5HT3 receptors." Neurogastroenterol Motil, 2002;14(2):151-9. PMID: 11975715.
- [other] UniProt P12872: MOTI_HUMAN, promotilin; peptide 26-47 is motilin (FVPIFTYGELQRMQEKERNKGQ). Read October 28, 2026. https://www.uniprot.org/uniprotkb/P12872/entry
Sources & Citations
Every study on this page was read from its PubMed record on October 28, 2026. Regulatory status comes from Drugs@FDA (openFDA) and the EMA medicines list, read the same day. Grey Peptides sells nothing and links to no vendor.
Medical Disclaimer: This content is for educational and informational purposes only. It is not medical advice, and nothing here is an instruction to obtain or use any compound. Talk to a licensed clinician about your own situation.